Notice that the fix was to use "Schrödinger’s Cat" instead of "Schrödinger's Cat". The fix was removing the single quote, as the script checked if there were characters that would run afoul of string escaping. The problem as it is has nothing to do with Unicode and was actually fixed by using a Unicode character.
That doesn't mean that there aren't any Unicode bugs in other tools, but that wasn't the issue in this particular case.
Handling of special character is usually a bigger problem than unicode. Just today, I tried to name a file with both a single quote and an exclamation point from bash shell. Ended up doing that with a GUI file manager.
History expansion will happen on the ! in double quotes:
$ ls "!$"
ls "'j-kidd'\''s file!'"
ls: cannot access 'j-kidd'\''s file!': No such file or directory
It won't happen on single-quotes:
$ ls '!$'
ls: cannot access !$: No such file or directory
The only issue is that you can't escape a single-quote within single quotes, so you have to do one of these '\'' (escape a single-quote block, a literal single quote, start a new single quote block).
Yep, that's an important and maybe non-obvious behavior of the shell:
"directly adjacent strings which are double quoted, "'single quoted or even'\ unquoted\ and\ possibly\ full\ of\ escape\ sequences\ 'get concatenated and count as a single parameter.'
Running touch on the above will create one file with very long name.
That doesn't mean that there aren't any Unicode bugs in other tools, but that wasn't the issue in this particular case.